The use of electrostatic techniques for coating surfaces is well known in the art. Typically, electrostatic techniques are used for paint coating wherein the powdered "paint" material is pneumatically forced through an electric field to cause the particles of the material to become charged. These particles are then directed to a target having an opposite charge. The electrostatic attraction between the target and the respective particles causes the powder to change its direction and flow around the target to contact exposed surfaces. In this manner, it is possible to obtain complete coverage of an exposed target surface and create a bond between the powder and the target. If the target is completely covered by previously applied or attracted particles, then the excess powder particles are allowed to simply fall to a conveyor or floor of the processing area to later be collected and reused.
In prior art painting operations, such over-spraying does not represent a problem since the systems are designed to incorporate an overspray to insure complete coverage of the target area and the excess powder is simply recycled and reused. Since the materials used in such operations are reusable, and since there is no consideration given concerning the possibility of bacterial growth, these prior art techniques are completely satisfactory. Typically, this prior art painting operation results in a forty percent to fifty percent excess paint powder that is injected into the operative coating area. Using normal exhaust systems and excess spray collection systems, the excess powder dissipates its charge and falls into a collection container at the base of the system, such as a hopper or a bin, and is carried back to the feed hopper and reintroduced for coating.
The application of such prior art systems to the coating of edible products with an edible coating results in the exposure of the excess spray to the possible growth of bacteria. Typical regulations governed by federal agencies require food handling facilities to be kept clean including machinery that is thoroughly cleaned (sometimes several times a day) to prevent the possibility that substances could accumulate and become bacterial breeding grounds. Further, typical food processing plants are labor intensive that would militate against permitting over-spray or excess powder to be released into the workplace. Therefore, prior art electrostatic coating technology fails to provide the necessary assurance against bacterial infestations and environmental cleanliness.